Systems and methods for performing in-frame cleaning

ABSTRACT

A system includes an electronic display panel that has a plurality of pixels configured to depict frames of image data. The electronic display also includes display driver circuitry configured to, for a first frame of image data representing first image content, modify a gate-to-source voltage of a transistor of a first pixel of the plurality of pixels to a content-dependent first gate-to-source voltage. Additionally, after modifying the gate-to-source voltage to the first gate-to-source voltage, the display driver circuitry is configured to program the first pixel by modifying the gate-to-source voltage to a gate-to-source programming voltage that differs from the first gate-to-source voltage and is based on image data associated with the pixel from the first frame of the image data. Furthermore, the display driver circuitry is configured to cause the plurality of pixels to emit light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/822,468, entitled “SYSTEMS AND METHODS FOR PERFORMING IN-FRAMECLEANING,” filed on Mar. 22, 2019, which is incorporated herein byreference in its entirety for all purposes.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

The present disclosure generally relates to reducing and/or eliminatingvisible changes in luminance that may occur when content (e.g., a stillimage) is displayed on a display for extended periods of time (e.g.,minutes, hours, days). As described below, in one embodiment, anin-frame cleaning technique may be utilized to keep a threshold voltageassociated with a transistor of display circuitry (e.g., a pixel of adisplay) from changing or to slow the change in threshold voltage thatmay occur when content is shown for extended periods of time. Inparticular, a content-dependent voltage (e.g., gate-to-source voltage)may be applied to the transistor before being programmed, which mayalter a voltage associated with the transistor and slow down oreliminate the accumulation of charge in the transistor that mayotherwise occur. Charge accumulation in the transistor over time ascontent (e.g., frames of video content, still images, etc.) is shown maycause the threshold voltage associated with the transistor to change,which in some cases, may cause visible changes to the content displayed(e.g., change in luminance, perceived change in coloration of content).Accordingly, by modifying the gate-to-source voltage of the transistorbefore programming (and/or after a previous emission of light from alight emitting diode (LED) associated with the transistor), chargeaccumulation may be reduced and/or eliminated, which may reduce theoccurrence of display irregularities attributable to changes inthreshold voltage of the transistor.

Furthermore, in-frame cleaning may also be utilized to reduce “imagesticking,” which refers to an image or portion of an image persisting,or still being displayed, longer than the image or portion thereofshould be displayed. For example, content from one frame of content maystill be visible to the human eye after a subsequent frame of content isdisplayed. As discussed below, performing in-frame cleaning mayaccelerate the recovery from a shift in threshold voltage. For example,a gap in threshold voltage between a first threshold voltage associatedwith relatively high gray-levels (e.g., relatively brighter content) andcontent relatively low gray-levels (e.g., relatively darker content) maycause image sticking. By shortening the time it takes to reduce the gapin threshold voltage, the occurrence of image sticking perceivable bythe human eye may be reduced and/or eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 is a schematic block diagram of an electronic device, inaccordance with an embodiment;

FIG. 2 is a perspective view of a notebook computer representing anembodiment of the electronic device of FIG. 1;

FIG. 3 is a front view of a hand-held device representing anotherembodiment of the electronic device of FIG. 1;

FIG. 4 is a front view of another hand-held device representing anotherembodiment of the electronic device of FIG. 1;

FIG. 5 is a front view of a desktop computer representing anotherembodiment of the electronic device of FIG. 1;

FIG. 6 is a front view and side view of a wearable electronic devicerepresenting another embodiment of the electronic device of FIG. 1;

FIG. 7 is a circuit diagram illustrating a portion of an array of pixelsof the display of FIG. 1, in accordance with an embodiment;

FIG. 8 is a circuit diagram of an example pixel driving circuit for apixel in the display of the electronic device of FIG. 1, in accordancewith an embodiment;

FIG. 9 is a graph illustrating drain-to-source current versusgate-to-source voltage of a transistor of the pixel driving circuit ofFIG. 8, in accordance with an embodiment;

FIG. 10 illustrates changes in threshold voltage and luminanceassociated with different content associated with transitions ofcontent, in accordance with an embodiment;

FIG. 11 illustrates the appearance of image content that is displayedafter different image content has been presented for an extended periodof time when in-frame cleaning is performed and when in-frame cleaningis not performed, in accordance with an embodiment;

FIG. 12 is flow diagram of a process for operating pixel circuitry, suchas the pixel driving circuitry of FIG. 8, in accordance with anembodiment;

FIGS. 13-16 each illustrate a circuit timing diagram for performingin-frame cleaning, programming image data, and emitting light, inaccordance with an embodiment; and

FIG. 17 illustrates three graphs showing effects on threshold voltage ofutilizing in-frame cleaning, in accordance with an embodiment.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions are made to achieve the developers'specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

Electronic displays are found in numerous electronic devices, frommobile phones to computers, televisions, automobile dashboards, and manymore. Individual pixels of the electronic display may collectivelyproduce images by permitting different amounts of light to be emittedfrom each pixel. This may occur by self-emission as in the case oflight-emitting diodes (LEDs), such as organic light-emitting diodes(OLEDs), or by selectively providing light from another light source asin the case of a digital micromirror device or liquid crystal display.In some cases, image data represented by an output of a display maychange due to changes in pixel operation over time. For example, when animage (e.g., a static image) is displayed for relatively longer periodsof time (e.g., minutes, hours, days) the appearance of the image maychange over time. Additionally, image sticking may occur, for example,when a transition from an image or piece of content that was displayedfor a relatively long time (e.g., minutes or hours or longer) to anotherimage occurs. For instance, when switching from relatively high-contrastcontent (e.g., content associated with relatively a high gray-leveldifference) to relatively low-contrast content (e.g., content associatedwith a relatively low gray-level difference), portions of the relativelyhigh-contrast content may persist on the display and be visible to thehuman eye.

Embodiments of the present disclosure relate to reducing and/oreliminating visible changes in luminance that may occur when content(e.g., a still image) is displayed on a display for extended periods oftime (e.g., minutes, hours, days). As described below, in oneembodiment, an in-frame cleaning technique may be utilized to keep athreshold voltage associated with a transistor of display circuitry(e.g., a pixel of a display) from changing or to slow the change inthreshold voltage that may occur when content is shown for extendedperiods of time. In particular, a content-dependent voltage (e.g.,gate-to-source voltage) may be applied to the transistor before beingprogrammed, which may alter a voltage associated with the transistor andslow down or eliminate the accumulation of charge in the transistor thatmay otherwise occur. Charge accumulation in the transistor over time ascontent (e.g., frames of video content, still images, etc.) is shown maycause the threshold voltage associated with the transistor to change,which in some cases, may cause visible changes to the content displayed(e.g., change in luminance, perceived change in coloration of content).For instance, a gap in threshold voltage associated with relatively highgray-levels and threshold voltage associated with relatively lowgray-levels may increase over time when content is shown for arelatively long period of time (e.g., minutes, hours, days).Accordingly, by modifying the gate-to-source voltage of the transistorbefore programming (and after a previous emission of light from a lightemitting diode (LED) associated with the transistor), chargeaccumulation may be reduced and/or eliminated, and the growth of adifference between threshold voltage associated with relatively highgray-levels and threshold voltage associated with relatively lowgray-levels may be decelerated, which may reduce the occurrence ofdisplay irregularities attributable to changes in threshold voltage ofthe transistor. Furthermore, by performing in-frame cleaning, whenshifting from content displayed for a relatively long time (e.g.,minutes, hours, days) to other content, decreasing a difference betweenthreshold voltage associated with relatively high gray-levels andthreshold voltage associated with relatively low gray-levels may beaccelerated, which may reduce and/or eliminate the occurrence of imagesticking.

A general description of suitable electronic devices that may performthe in-frame cleaning technique described herein and display imagesthrough emission of light from light-emitting components, such as an LED(e.g., an OLED) display, and corresponding circuitry are provided inthis disclosure. It should be understood that a variety of electronicdevices, electronic displays, and electronic display technologies may beused to implement the techniques described herein. With this in mind, ablock diagram of an electronic device 10 is shown in FIG. 1. As will bedescribed in more detail below, the electronic device 10 may representany suitable electronic device, such as a computer, a mobile phone, aportable media device, a tablet, a television, a virtual-realityheadset, a vehicle dashboard, or the like. The electronic device 10 mayrepresent, for example, a notebook computer 10A as depicted in FIG. 2, ahandheld device 10B as depicted in FIG. 3, a handheld device 10C asdepicted in FIG. 4, a desktop computer 10D as depicted in FIG. 5, awearable electronic device 10E as depicted in FIG. 6, or a similardevice.

The electronic device 10 shown in FIG. 1 may include, for example, aprocessor core complex 12, a local memory 14, a main memory storagedevice 16, an electronic display 18, input structures 22, aninput/output (I/O) interface 24, network interfaces 26, and a powersource 28. The various functional blocks shown in FIG. 1 may includehardware elements (including circuitry), software elements (includingmachine-executable instructions stored on a tangible, non-transitorymedium, such as the local memory 14 or the main memory storage device16) or a combination of both hardware and software elements. It shouldbe noted that FIG. 1 is merely one example of a particularimplementation and is intended to illustrate the types of componentsthat may be present in electronic device 10. Indeed, the variousdepicted components may be combined into fewer components or separatedinto additional components. For example, the local memory 14 and themain memory storage device 16 may be included in a single component.

The processor core complex 12 may carry out a variety of operations ofthe electronic device 10, such as provide image data for display on theelectronic display 18. The processor core complex 12 may include anysuitable data processing circuitry to perform these operations, such asone or more microprocessors, one or more application specific processors(ASICs), or one or more programmable logic devices (PLDs). In somecases, the processor core complex 12 may execute programs orinstructions (e.g., an operating system or application program) storedon a suitable article of manufacture, such as the local memory 14 and/orthe main memory storage device 16. In addition to instructions for theprocessor core complex 12, the local memory 14 and/or the main memorystorage device 16 may also store data to be processed by the processorcore complex 12. By way of example, the local memory 14 may includerandom access memory (RAM) and the main memory storage device 16 mayinclude read only memory (ROM), rewritable non-volatile memory such asflash memory, hard drives, optical discs, or the like.

The electronic display 18 may display image frames, such as a graphicaluser interface (GUI) for an operating system or an applicationinterface, still images, or video content. The processor core complex 12may supply at least some of the image frames. The electronic display 18may be a self-emissive display, such as an organic light emitting diodes(OLED) display, or may be a liquid crystal display (LCD) illuminated bya backlight. In some embodiments, the electronic display 18 may includea touch screen, which may allow users to interact with a user interfaceof the electronic device 10. The electronic display 18 may employdisplay panel sensing to identify operational variations of theelectronic display 18. This may allow the processor core complex 12 orthe electronic display 18 to adjust image data that is sent to theelectronic display 18 to compensate for these variations, therebyimproving the quality of the image frames appearing on the electronicdisplay 18.

The input structures 22 of the electronic device 10 may enable a user tointeract with the electronic device 10 (e.g., pressing a button toincrease or decrease a volume level). The I/O interface 24 may enableelectronic device 10 to interface with various other electronic devices,as may the network interface 26. The network interface 26 may include,for example, interfaces for a personal area network (PAN), such as aBluetooth network, for a local area network (LAN) or wireless local areanetwork (WLAN), such as an 802.11x Wi-Fi network, and/or for a wide areanetwork (WAN), such as a cellular network. The network interface 26 mayalso include interfaces for, for example, broadband fixed wirelessaccess networks (WiMAX), mobile broadband Wireless networks (mobileWiMAX), asynchronous digital subscriber lines (e.g., ADSL, VDSL),digital video broadcasting-terrestrial (DVB-T) and its extension DVBHandheld (DVB-H), ultra wideband (UWB), alternating current (AC) powerlines, and so forth. The power source 28 may include any suitable sourceof power, such as a rechargeable lithium polymer (Li-poly) batteryand/or an alternating current (AC) power converter.

In certain embodiments, the electronic device 10 may take the form of acomputer, a portable electronic device, a wearable electronic device, orother type of electronic device. Such computers may include computersthat are generally portable (such as laptop, notebook, and tabletcomputers) as well as computers that are generally used in one place(such as conventional desktop computers, workstations and/or servers).In certain embodiments, the electronic device 10 in the form of acomputer may be a model of a MacBook®, MacBook® Pro, MacBook Air®,iMac®, Mac® mini, or Mac Pro® available from Apple Inc. By way ofexample, the electronic device 10, taking the form of a notebookcomputer 10A, is illustrated in FIG. 2 in accordance with one embodimentof the present disclosure. The depicted computer 10A may include ahousing or enclosure 36, an electronic display 18, input structures 22,and ports of an I/O interface 24. In one embodiment, the inputstructures 22 (such as a keyboard and/or touchpad) may be used tointeract with the computer 10A, such as to start, control, or operate aGUI or applications running on computer 10A. For example, a keyboardand/or touchpad may allow a user to navigate a user interface orapplication interface displayed on the electronic display 18.

FIG. 3 depicts a front view of a handheld device 10B, which representsone embodiment of the electronic device 10. The handheld device 10B mayrepresent, for example, a portable phone, a media player, a personaldata organizer, a handheld game platform, or any combination of suchdevices. By way of example, the handheld device 10B may be a model of aniPod® or iPhone® available from Apple Inc. of Cupertino, Calif. Thehandheld device 10B may include an enclosure 36 to protect interiorcomponents from physical damage and to shield them from electromagneticinterference. The enclosure 36 may surround the electronic display 18.The I/O interfaces 24 may open through the enclosure 36 and may include,for example, an I/O port for a hard wired connection for charging and/orcontent manipulation using a standard connector and protocol, such asthe Lightning connector provided by Apple Inc., a universal serial bus(USB), or other similar connector and protocol.

User input structures 22, in combination with the electronic display 18,may allow a user to control the handheld device 10B. For example, theinput structures 22 may activate or deactivate the handheld device 10B,navigate user interface to a home screen, a user-configurableapplication screen, and/or activate a voice-recognition feature of thehandheld device 10B. Other input structures 22 may provide volumecontrol, or may toggle between vibrate and ring modes. The inputstructures 22 may also include a microphone may obtain a user's voicefor various voice-related features, and a speaker may enable audioplayback and/or certain phone capabilities. The input structures 22 mayalso include a headphone input may provide a connection to externalspeakers and/or headphones.

FIG. 4 depicts a front view of another handheld device 10C, whichrepresents another embodiment of the electronic device 10. The handhelddevice 10C may represent, for example, a tablet computer or portablecomputing device. By way of example, the handheld device 10C may be atablet-sized embodiment of the electronic device 10, which may be, forexample, a model of an iPad® available from Apple Inc. of Cupertino,Calif.

Turning to FIG. 5, a computer 10D may represent another embodiment ofthe electronic device 10 of FIG. 1. The computer 10D may be anycomputer, such as a desktop computer, a server, or a notebook computer,but may also be a standalone media player or video gaming machine. Byway of example, the computer 10D may be an iMac®, a MacBook®, or othersimilar device by Apple Inc. It should be noted that the computer 10Dmay also represent a personal computer (PC) by another manufacturer. Asimilar enclosure 36 may be provided to protect and enclose internalcomponents of the computer 10D such as the electronic display 18. Incertain embodiments, a user of the computer 10D may interact with thecomputer 10D using various peripheral input devices, such as inputstructures 22A or 22B (e.g., keyboard and mouse), which may connect tothe computer 10D.

Similarly, FIG. 6 depicts a wearable electronic device 10E representinganother embodiment of the electronic device 10 of FIG. 1 that may beconfigured to operate using the techniques described herein. By way ofexample, the wearable electronic device 10E, which may include awristband 43, may be an Apple Watch® by Apple Inc. However, in otherembodiments, the wearable electronic device 10E may include any wearableelectronic device such as, for example, a wearable exercise monitoringdevice (e.g., pedometer, accelerometer, heart rate monitor), or otherdevice by another manufacturer. The electronic display 18 of thewearable electronic device 10E may include a touch screen display 18(e.g., LCD, OLED display, active-matrix organic light emitting diode(AMOLED) display, and so forth), as well as input structures 22, whichmay allow users to interact with a user interface of the wearableelectronic device 10E.

The electronic display 18 for the electronic device 10 may include amatrix of pixels that contain light-emitting circuitry. Accordingly,FIG. 7 illustrates a circuit diagram including a portion of a matrix ofpixels in an active area of the electronic display 18. As illustrated,the electronic display 18 may include a display panel 60. Moreover, thedisplay panel 60 may include multiple unit pixels 62 (here, six unitpixels 62A, 62B, 62C, 62D, 62E, and 62F are shown) arranged as an arrayor matrix defining multiple rows and columns of the unit pixels 62 thatcollectively form a viewable region of the electronic display 18, inwhich an image may be displayed. In such an array, each unit pixel 62may be defined by the intersection of rows and columns, represented hereby the illustrated gate lines 64 (also referred to as “scanning lines”)and data lines 66 (also referred to as “source lines”), respectively.Additionally, power supply lines 68 may provide power to each of theunit pixels 62 (e.g., from power supply 78). The unit pixels 62 mayinclude, for example, a thin film transistor (TFT) coupled to aself-emissive pixel, such as an OLED, whereby the TFT may be a drivingTFT that facilitates control of the luminance of a display pixel 62 bycontrolling a magnitude of supply current flowing into the OLED of thedisplay pixel 62 or a TFT that controls luminance of a display pixel bycontrolling the operation of a liquid crystal.

Although only six unit pixels 62, referred to individually by referencenumbers 62A-62F, respectively, are shown, it should be understood thatin an actual implementation, each data line 66 and gate line 64 mayinclude hundreds or even thousands of such unit pixels 62. By way ofexample, in a color display panel 60 having a display resolution of1024×768, each data line 66, which may define a column of the pixelarray, may include 768 unit pixels, while each gate line 64, which maydefine a row of the pixel array, may include 1024 groups of unit pixelswith each group including a red, blue, and green pixel, thus totaling3072 unit pixels per gate line 64. It should be readily understood,however, that each row or column of the pixel array any suitable numberof unit pixels, which could include many more pixels than 1024 or 768.In the presently illustrated example, the unit pixels 62 may represent agroup of pixels having a red pixel (62A), a blue pixel (62B), and agreen pixel (62C). The group of unit pixels 62D, 62E, and 62F may bearranged in a similar manner. Additionally, in the industry, it is alsocommon for the term “pixel” may refer to a group of adjacentdifferent-colored pixels (e.g., a red pixel, blue pixel, and greenpixel), with each of the individual colored pixels in the group beingreferred to as a “sub-pixel.” In some cases, however, the term “pixel”refers generally to each sub-pixel depending on the context of the useof this term.

As illustrated, the electronic display 18 may include an array of pixels62 (e.g., self-emissive pixels). The electronic display may include anysuitable circuitry to drive the pixels 62. In the example of FIG. 7, theelectronic display 18 includes a controller 69, a source driverintegrated circuit (IC) 70, and a gate driver IC 72. The source driverIC 70 and gate driver IC 72 may drive individual of the self-emissivepixels 62. In some embodiments, the source driver IC 70 and the gatedriver IC 72 may include multiple channels for independently drivingmultiple of the self-emissive pixel 62. Each of the pixels 62 mayinclude any suitable light-emitting element, such as a LED, one exampleof which is an OLED. However, any other suitable type of pixel,including non-self-emissive pixels (e.g., liquid crystal, digitalmicromirror) may also be utilized.

The controller 69, which may include a chip, such as a processor orapplication specific integrated circuit (ASIC), that controls variousaspects (e.g., operation) of the electronic display 18 and/or thedisplay panel 60. For instance, the controller 69 may receive image data74 from the processor core complex indicative of light intensities forthe light outputs for the pixels 62. In some embodiments, the controller69 may be coupled to the local memory 14 and retrieve the image data 74from the local memory 14. The controller 69 may control the pixels 62 byusing control signals to control elements of the pixels 62. Forinstance, the pixels 62 may include any suitable controllable element,such as a transistor, one example of which is a MOSFET. The pixels 62,which may be self-emissive, may include any suitable controllableelement, such as a transistor, one example of which is a MOSFET.However, any other suitable type of controllable elements, includingthin film transistors (TFTs), p-type and/or n-type MOSFETs, and othertransistor types, may also be used. The controller 69 may controlelements of the pixels 62 via the source driver IC70 and the gate driverIC 72. For example, the controller 69 may send signals to the sourcedriver IC 70, which may send signals (e.g., timing information/imagesignals 76) to the pixels 62. The gate driver IC 72 may provide/removegate activation signals to activate/deactivate rows of unit pixels 62via the gate lines 64 based on timing information/image signals 76received from the controller 69.

In some embodiments, the controller 69 may be included in the sourcedriver IC 70. Additionally, the controller 69 or source driver IC 70 mayinclude a timing controller (TCON) that determines and sends the timinginformation/image signals 76 to the gate driver IC 72 to facilitateactivation and deactivation of individual rows of unit pixels 62. Inother embodiments, timing information may be provided to the gate driverIC 72 in some other manner (e.g., using a controller 80 that is separatefrom or integrated within the source driver IC 70). Further, while FIG.7 depicts only a controller 69 and a single source driver IC 70, itshould be appreciated that other embodiments may utilize multiplecontrollers 69 and/or multiple source driver ICs 70 to provide timinginformation/image signals 76 to the unit pixels 62. For example,additional embodiments may include multiple controller 69 and/ormultiple source driver ICs 70 disposed along one or more edges of thedisplay panel 60, with each controller 69 and/or source driver IC 70being configured to control a subset of the data lines 66 and/or gatelines 64.

In some embodiments, the pixel 62 may include a number of circuitcomponents to enable the respective LED to produce light for aprescribed amount of time or produce a particular gray level. By way ofexample, FIG. 8 illustrates a pixel driving circuit 90 that may includea number of semiconductor devices that may coordinate the transmissionof data signals to an organic light-emitting diode (LED) 92 of arespective pixel 62. In one embodiment, the pixel driving circuit 90 mayreceive input signals (e.g., emission signals 1 and 2, scan signals 1and 2), which may be coordinated in a manner to cause the pixel drivingcircuit 90 to display image data and transmit a test data signal used todetermine the OLED voltage (VoLED) (e.g., voltage at Node 3) of the OLED92.

With this in mind, the pixel driving circuit 90 may include, in oneembodiment, N-type semiconductor devices and P-type semiconductordevices, as shown in FIG. 8. Although the following description of thepixel driving circuit 90 is illustrated with the N-type semiconductordevices and the P-type semiconductor devices, it should be noted thatthe pixel driving circuit 90 may be designed using any suitablecombination of N-type or P-type semiconductor devices.

In addition to the semiconductor devices, the pixel driving circuit 90may include a capacitor 94 that may store data provided via data line96. The close proximity between the various circuit components of thepixel driving circuit 90 and the various voltage sources (e.g., VDD,VSS) may also create parasitic capacitance within the pixel drivingcircuit 90. The capacitor 94 and the parasitic capacitance of the pixeldriving circuit 90 may be combined in a capacitance ratio thatrepresents the total capacitance of the pixel driving circuit 90.

In some embodiments, one or more of the semiconductors (e.g., TFTs) ofthe pixel driving circuit 90 may produce a current in response to thevoltage received via the data line 96. When the emission signal (e.g.,EM) is provided to a gate of the respective switch, the OLED 92 mayreceive a current that corresponds to the data stored in the capacitor94. As the OLED 92 illuminates in response to receiving the current(I_(OLED)), a voltage (e.g., V_(OLED)) at Node 3 may change when theOLED 92 receives the same amount of current over time. This change involtage is representative of the aging effects of the OLED 92.

In some cases, the appearance of images displayed via the electronicdisplay 18 may change over time due to a threshold voltage of atransistor changing over time. In other words, the minimumgate-to-source voltage sufficient to form a conducting path betweensource and drain terminals of the transistor may change over time. Forexample, a threshold voltage of a transistor 100 of the pixel drivingcircuit 90 may change over time when the same image data is presentedvia the electronic display 18 for extended periods of time (e.g.,minutes, hours, days). Such a shift in threshold voltage may causechanges in the content that is shown via the electronic display 18. Thatis, the pixel driving circuit 90 may emit light with differentcharacteristics as a result of the threshold voltage changing. Forexample, pixels emitting light associated with relatively lowgray-levels that would normally appear dark, may appear brighter overtime. Conversely, relatively high gray-levels that would normally appearrelatively bright may darken over time.

To help illustrate this, FIG. 9 is a graph 120 illustratingdrain-to-source current (represented by axis 122) versus gate-to-sourcevoltage (represented by axis 124). It should be noted that thedrain-to-source current is proportional to the luminance (“L”)associated with the pixel driving circuit 90. The graph 120 alsoincludes a first curve 126 and a second curve 128. The curves 126, 128are representative of a pixel's operation at two different points intime. For example, the first curve 126 may be associated with the pixeldriving circuit 90 at a first time, and the second curve 128 may beassociated with the pixel driving circuit 90 at a second, later time. Asillustrated, the second curve 128 is generally shifted to the rightcompared to the first curve. As such, a threshold voltage may beassociated with a relatively higher luminance on the first curve 126compared to the second curve 128. For example, line 130 shows athreshold voltage (e.g., gate-to-source voltage) associated with oneluminance (e.g., luminance associated with point 132) on the first curve126, while on the second curve 128, the same voltage may be associatedwith a lower luminance (e.g., a luminance associated with point 134). Inother words, the graph 120 illustrates that when there is a change orshift in threshold voltage, the luminance level associated with thethreshold voltage may also change.

As discussed above, there may be a gap in threshold voltage associatedwith different pixels included in display circuitry, especially whenthere is a contrast in the content being displayed by the pixels.Bearing this in mind, FIG. 10 illustrates a transition from a firstpiece of content 140 to second piece of content 142 to a third piece ofcontent 144 to a fourth piece of content 146. FIG. 10 also includesgraph 148, which illustrates a threshold voltage of transistors (e.g.,transistor 100) for one or more pixels (e.g., pixels 62 of the displaypanel 60) displaying content at a relatively higher gray-level(represented by line 149) and a threshold voltage for one or more pixelsdisplaying content at a relatively lower gray-level (represented by line150), and graph 152, which is representative of current associated withtransistors (e.g., transistor 100) in pixels included in displaycircuitry (e.g., pixels 62 of the display panel 60) or luminanceassociated with the pixels. More specifically, each of the pieces ofcontent 140, 142, 144, 146 pertain to content associated with fourpixels: a first pixel 154, a second pixel 155, a third pixel 156, and afourth pixel 157.

In the first frame of content 140, the pixels 154, 155, 156, 157 mayeach be associated with a median gray-level “MG.” Because each of thepixels 154, 155, 156, 157 is associated with the same gray level, athreshold voltage associated with a transistor (e.g., transistor 100) ofeach of the pixels 154, 155, 156, 157 may be equal or substantiallyequal, as shown by the lines 149, 150 in the graph 148. Furthermore,current associated with the transistor (e.g., transistor 100) of each ofthe pixels 154, 155, 156, 157 and luminance associated with the pixels154, 155, 156, 157 may be equal or substantially equal, as representedby line 158 and line 159 of graph 152.

A transition to the second frame of content 142 may occur. Asillustrated, in the second frame of content 142, each of the pixels 154,155, 156, 157 may be associated with a gray-level that differs from acorresponding gray-level of the first frame of content 140. For example,in the second frame of content 142, the first pixel 154 and fourth pixel157 are both associated with a relatively high gray-level “HG” (e.g.,G255), while the second pixel 155 and third pixel 156 are bothassociated with a relatively low gray-level “LG” (e.g., G0).

Threshold voltages associated with transistors (e.g., transistor 100) inthe pixels 154, 155, 156, 157 are shown in the graph 148. In particular,line 149 may correspond to the first pixel 154 and the fourth pixel 157,and line 150 may correspond to the second pixel 155 and the third pixel156. As illustrated in the graph 148, a gap in threshold voltage mayoccur, and the gap may grow over time. For instance, a display (e.g.,display 18) that includes the pixels 154, 155, 156, 157 may display manyframes of content that are equivalent to the second frame of content 142over an extended period of time (e.g., minutes, hours, days), duringwhich time the gap between the threshold voltages indicated by the lines149, 150 may grow.

The changes in luminance associated with the transition from the firstframe of content 140 to the second frame of content 142 are reflected inthe graph 152. For example, line 158 corresponds to the first pixel 154and the fourth pixel 157, while the line 159 corresponds to the secondpixel 155 and the third pixel 156. As illustrated, as the luminanceassociated with the pixels 154, 155, 156, 157 (and the currentassociated with transistors of the pixels 154, 155, 156, 157) may changeas the threshold voltage changes. For example, as a threshold voltageassociated with the first pixel 154 and the fourth pixel 157 increases,the luminance of the first pixel 154 and fourth pixel 157 may decrease.Conversely, as a threshold voltage associated with the second pixel 155and the third pixel 156 decreases, the luminance of the second pixel 155and third pixel 156 may increase. In other words, as the gap inthreshold voltage increases, a gap in luminance between the relativelyhigher luminance and the relatively lower luminance may decrease.

At another point in time, the pixels 154, 155, 156, 157 may be commandedto display image data associated with the median gray-level, and thethird frame of content 144 may be displayed. However, as illustrated inFIG. 10, the displayed content associated with the pixels 154, 155, 156,157 may differ from the content shown during the first frame of content142 even though both the pixels 154, 155, 156, 157 are associated withthe same gray-levels during the first frame of content 140 and the thirdframe of content 144. Such a phenomenon may be perceived to the humaneye as image sticking. In particular, the difference between thedisplayed content of the pixels 154, 155, 156, 157 during the thirdframe of content 144 compared to the first frame of content 140 isattributable to the accumulation of the shift in threshold voltage thatoccurred during a time associated with the second frame of content. Inother words (and as illustrated by the graph 148), to show the mediangray-level content, the gap in threshold voltage between the lines 149,150 will decrease. However, until the gap in threshold voltage shrinksto a sufficient level, while the gap in threshold voltage is decreasing,the luminance associated with each of the pixels 154, 155, 156, 157 maynot match the luminance that the pixels 154, 155, 156, 157 werecommanded to have. When the gap in threshold voltage decreases, thedisplayed content may correspond to the gray-levels that the pixels 154,155, 156, 157 were commanded to have. For example, the fourth frame ofcontent 146, which has the same gray-levels as the third frame ofcontent 146, may correspond to a time when the gap in threshold voltagehas been sufficiently reduced and/or eliminated.

Keeping the discussion of FIG. 9 and FIG. 10 in mind, the presentdisclosure relates to techniques that reduce shifts or gaps in thresholdvoltage associated with pixel circuitry (e.g., while content is shownfor an extended period of time, such as minutes, hours, days, orlonger), such as the pixel driving circuit 90. Additionally, thepresently disclosed techniques may accelerate reducing a gap inthreshold voltage when transitioning between different content. Inparticular, the present application relates to a technique referredherein as “in-frame cleaning,” which, as discussed below, is generallyperformed by performing operations that change a gate-to-source voltageassociated with a transistor prior to programming the pixel circuitry.For instance, the presently disclosed techniques may be performed usingthe circuitry illustrated in FIG. 5 and FIG. 8. More specifically, thegate-to-source voltage may by associated with a gate (e.g., NODE2) andsource (e.g., NODE1) of the transistor 100 of FIG. 8, which may be anoxide thin film transistor. Furthermore, as discussed below, thegate-to-source voltage may become a value that is dependent upon imagedata (e.g., a gray-level) associated with the pixel.

Continuing with the drawings, FIG. 11 illustrates the appearance ofimage content 160 as well as how a different image content 161 appearswhen in-frame cleaning is performed and when in-frame cleaning is notperformed. In particular, the image content 160 generally corresponds tothe second frame of content 142 of FIG. 10, and the image content 161generally corresponds to third frame of content 144 of FIG. 10. In otherwords, the image content 160 may be displayed via the electronic display18 of the electronic device 10 at a first time. As illustrated, theimage content 160 includes light regions (e.g., region 162) and darkregions (e.g., region 164). The region 162 may be associated with arelatively high gray-level, whereas the region 164 may be associatedwith a relatively low gray-level. At a second time, the pixels of theelectronic display 18 may be commanded (e.g., via the controller 69) todisplay different content, such as image content associated with amedian gray-level.

Without in-frame cleaning, the image content 161A may be presented viathe electronic display 18. As illustrated, the regions 162B and regions164B may still be perceivable in the form of image sticking. In otherwords, as respectively shown by region 162B and the region 164B,remnants of the region 162A and region 164A perceivable to the human eyemay still persist on the electronic display 18 while other content isdisplayed. Conversely, as illustrated by the image content 161B, whenin-frame cleaning is performed, image sticking may be less perceptibleor not occur. For example, the region 162C and region 164C may be muchless perceptible respectively compared to the region 164A and region164B, and, in some embodiments, the region 162C and region 164C may notbe visible. For instance, in embodiments in which the image content 160is lower in contrast (e.g., associated with a smaller gray-leveldifference between the region 162A and the region 164A), the imagecontent 161B may appear uniform to the human eye. In other words, agray-level associated with the region 162C may be equal to a gray-levelassociated with the region 164C, or a difference between the gray-levelassociated with the region 162C and the gray-level associated with theregion 164C may not be perceptible to the human eye.

Also illustrated in the FIG. 11 is image content 161C, which isrepresentative of an in-frame cleaning goal. As illustrated, the imagecontent 161C is uniformly gray-level. In other words, while the imagecontent 161C may include regions (e.g., regions 162), because eachregion has the same color, to the human eye, the regions areindistinguishable from one another. As mentioned above, image contentsuch as the image content 161C may be achieved when there is smallerdifference in gray-level contrast between the regions 162 in imagecontent that precedes the image content 161C. For instance, inembodiments of the image content 160 in which the image content 160 islower in contrast, the image content 161C may displayed.

Continuing with the discussion of in-frame cleaning, FIG. 12 is a flowdiagram of a process 180 for operating pixel circuitry. The process 180may be performed by the electronic device 10. More specifically, theprocess 180 may be performed utilizing the electronic display panelcircuitry depicted in FIG. 5, which may include the pixel drivingcircuit 90 shown in FIG. 8. For example, the controller 69 may executeinstructions stored in the local memory 14 or the main memory storagedevice 16 to cause the gate driver IC 72 and/or source driver IC 70 tosend signals to cause the operations discussed below to occur.

At process block 182, the controller 69 may cause in-frame cleaning tobe performed. As will be discussed below, performing in-frame-cleaningmay entail causing a gate-to-source voltage associated with thetransistor 100 to shift in a content-dependent manner. In other words,the resulting gate-to-source voltage may be dependent upon the imagedata (e.g., a gray-level associated with content) previously programmedonto the pixel driving circuit 90 and/or image data about to beprogrammed onto the pixel driving circuit 90. For example, thegate-to-source voltage applied during in-frame cleaning differs from thegate-to-source voltage present during programming of the pixel drivingcircuit 90.

At process block 184, the controller 69 may cause image data to beprogrammed on the pixel driving circuit 90. For example, the controller69 may cause the source driver IC 70 to send a signal to cause imagedate to be programmed onto the pixel driving circuit 90.

At process block 186, the controller 69 may cause the OLED 92 of thepixel driving circuit 90 to emit light. For example, as discussed below,the controller 69 may send signals that cause the OLED 92 to emit lightin accordance with the image data associated with the programmingperformed at process block 184.

It should be noted that the process 180 may repeated. For example, insome embodiments, the process 180 may be performed for each frame ofimage data. In other embodiments, the process 180 may be performed basedon a refresh rate associated with the electronic display 18. Forexample, if the electronic display 18 has a refresh rate of sixty hertz,the process 180 may be performed sixty times per second. In general,performing the process 180 (e.g., performing in-frame cleaning) ondisplays 18 with relatively higher refresh rates (e.g., sixty hertz, 120hertz, or greater than 120 hertz) may result in less changes inluminance compared to displays 18 with relatively lower refresh rates(e.g., 30 hertz or less than 30 hertz) because the in-frame cleaning maybe performed more frequently, thus causing less charge accumulationassociated with maintaining a gate-to-source voltage similar or equal toa gate-to-source voltage experienced during programming and/or once thepixel driving circuit 90 is programmed.

FIGS. 13-16 each illustrate circuit timing diagrams that may be utilizedwith the pixel driving circuit 90 to perform in-frame cleaning,programming, and emitting in accordance with the process 180. Forexample, FIG. 13 includes a circuit timing diagram 200, which includessignals 202, 204, 206, 208. The signal 202 is representative of signalson odd scan lines, signal 204 is representative of signals on even scanlines, signal 206 is representative of an emission signal (e.g., EM inFIG. 8), and signal 208 is representative of an anode reset signal(e.g., AR in FIG. 8). It should be noted that the signal 206 may bepresented in an inverse manner (e.g., low state is indicative ofemission being possible (based on the status of other signals)). Thecircuit timing diagram 200 begins during a first emission period 210,which may end upon stress 218 (more specifically, an on stress 220A)being applied to odd scan lines or, for pixels associated with even scanlines, when an on stress 220B is applied to even scan lines and when ananode reset signal is no longer being sent (e.g., as indicated by thesignal 208). At a later time, the status of the emission signal 206 ismodified (e.g., ceased to be sent), and a threshold voltage stress 222is applied to the scan lines (e.g., scan lines in FIG. 8) as indicatedby the signals 202, 204. In general, the on stress 220 and the thresholdvoltage stress 222 are stresses that can be sent to account for changesto pixel circuitry (e.g., pixel driving circuit 90) that mayrespectively occur when the pixel circuitry switches to an on state andfrom programming a threshold voltage onto a transistor, such as thetransistor 100. During the on stress 220 and threshold voltage stress222 periods, the gate-to-source voltage associated with the transistormay change from a gate-to-source voltage that is associated with thetransistor when programmed. In some cases, such as for relatively highgray-levels or relatively low gray-levels, the gate-to-source voltageassociated with in-frame cleaning may generally be generally similar toa programming voltage associated with a generally inverse gray-level.For example, if the gate-to-source voltage associated with thetransistor 100, when programmed, has a first voltage associated with arelatively low gray-level, as a result of the on stress 220 andthreshold voltage stress 222, the transistor 100 may experience agate-to-source voltage that is typically experienced with relativelyhigh gray-levels. In other words, the gate-to-source voltage experiencedue to stress being applied is content dependent.

Programming of the pixel driving circuit 90 may occur near the end ofthe threshold voltage stress 222 being applied or after the thresholdvoltage stress is no longer applied but before the signals 206, 208change state. That is, as discussed above, programming occurs beforeemission. During programming, the gate-to-source voltage associated withthe transistor 100 may shift to a voltage that is associated with imagedata that is programmed into the pixel driving circuit 90. For example,if the image data is associated with a high gray-level, onegate-to-source voltage may be applied to program the pixel drivingcircuit 90. In a range of potential gate-to-source voltages that may beassociated with the transistor (e.g., a range from a first voltageassociated with very low gray-levels to a second voltage associated withvery high gray-levels), such a voltage may be in the opposite part ofthe range as compared to a voltage experienced during in-frame cleaning.By applying a different voltage during in-frame cleaning, the likelihoodof accumulation that can cause shifts to the threshold gate-to-sourcevoltage of the transistor 100 is vastly reduced. For example, byutilizing in-frame cleaning, any changes to the threshold gate-to-sourcevoltage may produce changes in luminance that are undetectable orotherwise invisible to the human eye. Furthermore, after programming,another emission period 228 may occur (e.g., as indicated by activationof the signals 206, 208).

Continuing with the drawings, FIG. 14 shows a circuit timing diagram 240of another embodiment for performing in-frame cleaning. The circuittiming diagram 240 is generally similar to the circuit timing diagram200 of FIG. 13, but differs in several aspects. For example, asillustrated, an on stress 220 and threshold voltage stress 222 may beapplied, but the threshold voltage stress 222 may generally be shorterin duration compared to the threshold voltage stress 222 of FIG. 13.Furthermore, an off stress 242 may be applied (e.g., after the thresholdvoltage stress 222). Similar to the on stress 220 and the thresholdvoltage stress 222, the off stress 242 may be applied to account forchanges to the transistor 100 (e.g., changes that occur from ceasing tosend a signal via one or more scan lines). Additionally, a second signal244 may be sent to cause programming of pixel circuitry prior toemission.

FIG. 15 depicts a circuit timing diagram 280 of another embodiment forperforming in-frame cleaning. The circuit timing diagram is generallysimilar to the circuit timing diagram 240 of FIG. 14, but differs inseveral aspects. In particular, a first scan line signal 282, may besent but may have a shorter duration than the combined duration of theon stress 220 and threshold voltage stress 222 of FIG. 14. However, asdepicted in FIG. 15, an on stress 220 may be applied. Furthermore, asecond scan line signal 284 may be sent to cause programming of pixelcircuitry prior to emission, which may occur after the second scan linesignal 284 as indicated by the signals 206, 208.

FIG. 16 depicts a circuit timing diagram 320 of another embodiment forperforming in-frame cleaning. In general, the circuit timing diagram 320is generally similar to the circuit timing diagram 280 of FIG. 15, butdiffers in several aspects. For example, while scan signals 322, 324generally correspond to the scan line signals 282, 284 of the circuittiming diagram 280, an off stress 242 is applied rather between the scanline signals 322, 324 instead of an on stress 220. Furthermore, emissionsignal 206 may be terminated earlier (e.g., at the same time as theanode reset signal 208). The second scan line signal 324 may be send tocause programming of the transistor 100 prior to emission.

FIG. 17 illustrates three graphs showing the effect on threshold voltageof utilizing various embodiments of in-frame cleaning discussed above.In particular, FIG. 17 includes graph 250, graph 252, and graph 254,each of which illustrate threshold voltage during a transition from afirst frame of content 140 to a second frame of content 142 to a thirdframe of content 142 relative to threshold voltage that may occur whenin-frame cleaning is not performed. For example, as discussed above,line 149 is representative of a threshold voltage of transistors (e.g.,transistor 100) of the first pixel 154 and the fourth pixel 157, whileline 150 is representative of threshold voltage associated withtransistors of the second pixel 155 and the third pixel 156.Additionally, it should be noted that the shading of the third frame ofcontent 144 is indicative of when in-frame cleaning is not performed.

The graph 250 is associated with when an on-stress bias is utilized. Aline 256 represents threshold voltage associated with the first pixel154 and the fourth pixel 157, and a line 258 is representative ofthreshold voltage associated with transistors of the second pixel 155and the third pixel 156. As illustrated, relative to the lines 149, 150,there is a smaller gap between the lines 256, 258.

The graph 252 is associated with when an off-stress bias is utilized. Aline 260 represents threshold voltage associated with the first pixel154 and the fourth pixel 157, and a line 262 is representative ofthreshold voltage associated with the second pixel 155 and the thirdpixel 156. As illustrated, relative to the lines 149, 150, there is asmaller gap between the lines 256, 258.

The graph 252 is associated with when both an on-stress and off-stressare utilized. A line 264 represents threshold voltage associated withthe first pixel 154 and the fourth pixel 157, and a line 266 isrepresentative of threshold voltage associated the second pixel 155 andthe third pixel 156. As illustrated, relative to the lines 149, 150,there is a smaller gap between the lines 256, 258. Accordingly, each ofthe graphs 250, 252, 254 demonstrate that performing in-frame cleaningreduces a gap in threshold voltage. As discussed above, by reducing agap in threshold voltage (or the rate at which such a gap forms), aquicker recovery from the gap in threshold voltage may occur whendifferent content is to be presented. A faster recovery from the gap inthreshold voltage enables content that more closely corresponds to imagedata to be displayed earlier, which may reduce the occurrence of and/oreliminate image sticking and/or perceivable image artifacts.

Each of the illustrated embodiments for performing in-frame cleaning mayresult in the achieved technical effects described above. For example,the formation of drifts or gaps in threshold voltage (e.g., associatedwith a transistor in pixel circuitry) may be greatly reduced and/oreliminated by performing in-frame cleaning when content is shown forextended periods of time (e.g., minutes, hours, days). Moreover, whencontent is displayed after other content has been presented for anextended period of time, a gap in threshold voltage may be more quicklyreduced. By reducing the rate at which gaps in threshold voltage occurand by accelerating the rate at which gaps in threshold voltage areclosed, changes in luminance perceivable by the human eye that mayresult from changes in threshold voltage may be reduced and/oreliminated. In particular, the in-frame cleaning techniques describedherein may cause a gate-to-source voltage of a transistor to be modifiedto a content-dependent voltage prior to being modified again duringprogramming of a pixel, which may reduce the occurrence of accumulationin threshold voltage as well as accelerate the recovery from anaccumulation in threshold voltage.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

The techniques presented and claimed herein are referenced and appliedto material objects and concrete examples of a practical nature thatdemonstrably improve the present technical field and, as such, are notabstract, intangible or purely theoretical. Further, if any claimsappended to the end of this specification contain one or more elementsdesignated as “means for [perform]ing [a function] . . . ” or “step for[perform]ing [a function] . . . ”, it is intended that such elements areto be interpreted under 35 U.S.C. 112(f). However, for any claimscontaining elements designated in any other manner, it is intended thatsuch elements are not to be interpreted under 35 U.S.C. 112(f).

What is claimed is:
 1. A system, comprising: an electronic display panelcomprising a plurality of pixels configured to depict frames of imagedata; and display driver circuitry configured to, for a first frame ofimage data representing first image content: modify a gate-to-sourcevoltage of a transistor of a first pixel of the plurality of pixels to afirst gate-to-source voltage, wherein the first gate-to-source voltageis content-dependent; after modifying the gate-to-source voltage to thefirst gate-to-source voltage, program the first pixel by modifying thegate-to-source voltage to a gate-to-source programming voltage based onimage data associated with the first pixel from the first frame of theimage data, wherein the gate-to-source programming voltage differs fromthe first gate-to-source voltage; and cause the plurality of pixels toemit light to display the first image content after modifying thegate-to-source voltage to the gate-to-source programming voltage.
 2. Thesystem of claim 1, wherein the transistor is configured to cause drivingof a light emitting diode (LED) of the first pixel of the plurality ofpixels.
 3. The system of claim 1, wherein the transistor comprises athin film transistor.
 4. The system of claim 3, wherein the transistorcomprises an oxide thin film transistor.
 5. The system of claim 1,wherein modifying the gate-to-source voltage of the transistor of thefirst pixel to the first gate-to-source voltage is configured to reducean occurrence of a shift in a threshold voltage associated with thetransistor.
 6. The system of claim 5, wherein modifying thegate-to-source voltage of the transistor of the first pixel to the firstgate-to-source voltage is configured to more effectively reduce theoccurrence of the shift in threshold voltage the higher a refresh rateassociated with the electronic display panel is.
 7. The system of claim1, wherein the first gate-to-source voltage is configured to range froma second gate-to-source voltage to a third gate-to-source voltage,wherein the second gate-to-source voltage is associated with arelatively low gray-level, and the third gate-to-source voltage isassociated with a relatively high gray-level.
 8. The system of claim 7,wherein the gate-to-source programming voltage corresponds to the secondgate-to-source voltage, and the gate-to-source first voltage correspondsto the third gate-to-source voltage.
 9. The system of claim 1, whereinthe electronic display panel comprises a plurality of scan linescommunicatively coupled to the display driver circuitry, wherein thedisplay driver circuitry is configured to cause a first stress to beapplied to the transistor to modify the gate-to-source voltage of thetransistor of the first pixel of the plurality of pixels to the firstgate-to-source voltage.
 10. The system of claim 9, wherein the displaydriver circuitry is configured to apply a second signal to a scan lineof the plurality of scan lines to cause programming of the transistorprior to causing the plurality of pixels to emit light.
 11. A method,comprising, for a first frame of image data representing first imagecontent: modifying, via display driver circuitry, a gate-to-sourcevoltage of a transistor of a pixel of display circuitry from a firstvoltage to a second voltage, wherein the second voltage iscontent-dependent and different than the first voltage; after modifyingthe gate-to-source voltage from the first voltage to the second voltage,programming, via the display driver circuitry, the pixel by modifyingthe gate-to-source voltage to be a third voltage, wherein the thirdvoltage differs from the second voltage and is based on image dataassociated with the pixel from the first frame of the image data; andcausing, via the display driver circuitry, the pixel to emit light todisplay the first image content after modifying the gate-to-sourcevoltage from the second voltage to the third voltage.
 12. The method ofclaim 11, wherein the first voltage and the third voltage aresubstantially equal.
 13. The method of claim 11, wherein the modifyingthe gate-to-source voltage from the first voltage to the second voltageis configured to reduce visible changes in luminance associated with thepixel by reducing an occurrence of a change in a threshold voltage ofthe transistor.
 14. The method of claim 11, wherein modifying thegate-to-source voltage from the first voltage to the second voltagecomprises applying a voltage to a scan line included in the displaycircuitry.
 15. A non-transitory, computer-readable medium comprisinginstructions that, when executed by display driver circuitry, areconfigured to cause the display driver circuitry to, for a first frameof image data representing image content: modify a gate-to-sourcevoltage of a transistor of a pixel of display circuitry from a firstvoltage to a second voltage, wherein the second voltage iscontent-dependent, different than the first voltage, and associated witha relatively low gray-level; after modifying the gate-to-source voltagefrom the first voltage to the second voltage, program the pixel bycausing the gate-to-source voltage to become a third voltage, whereinthe third voltage differs from the second voltage, is associated with arelatively high gray-level, and is based on image data associated withthe pixel from the first frame of the image data; and cause the pixel toemit light to display the image content after modifying thegate-to-source voltage from the second voltage to the third voltage. 16.The non-transitory, computer-readable medium of claim 15, wherein theinstructions are configured to cause the display driver circuitry tomodify the gate-to-source voltage of the transistor from the firstvoltage to the second voltage at a rate corresponding to a refresh rateassociated with the display driver circuitry.
 17. The non-transitory,computer-readable medium of claim 15, wherein the second voltagecorresponds to a gray-level associated with image data of the firstframe of image data.
 18. The non-transitory, computer-readable medium ofclaim 15, wherein the instructions are configured to modify thegate-to-source voltage of the transistor from the first voltage to thesecond voltage by applying one or more voltage stresses to a scan lineassociated with the pixel prior to programming the pixel.
 19. Thenon-transitory, computer-readable medium of claim 15, wherein modifyingthe gate-to-source voltage of the transistor from the first voltage tothe second voltage is configured to reduce an accumulation of charge inthe transistor.
 20. The non-transitory, computer-readable medium ofclaim 15, wherein the transistor comprises a thin film transistor.